Abstract

Numerical simulations play an important role in therapeutic ultrasound treatments. Simulations can help with transducer design, retroactively analyze temperature patterns for insight into treatment effectiveness, and ultimately be used for patient treatment planning. Our group has developed a rapid 3D simulation tool for ultrasound beam propagation named the hybrid angular spectrum (HAS) method. HAS is an extension of the traditional angular spectrum approach that uses fast Fourier transforms to alternate between the spatial frequency domain and the space domain as the beam propagates through inhomogeneous tissue regions. In this presentation, we briefly cover the physical and algorithmic principles underlying the HAS technique, then give examples of its use in two promising high-intensity focused ultrasound (HIFU) applications. First, we employ it to retrospectively predict the heating efficiency of transcranial treatments of 14 patients undergoing treatment for essential tremor using a large phased-array transducer. Phase aberration of the beams caused by skull irregularities is a major effect and must be modeled carefully for accurate results. Second, we model the extent of the phase aberration to be expected in our group’s recently developed MRI/HIFU breast treatment system and show a correlation with the degree of breast tissue inhomogeneity in the path of the beam.